Immunohistochemistry (IHC) staining systems provide visual localization of specific proteins within tissue sections. They are fundamental tools in pathology diagnostics and biomedical research, enabling the identification, distribution, and relative abundance of target antigens in situ.

Basic Concept

Immunohistochemistry combines principles of immunology and histology. Specific antibodies bind to target antigens in fixed tissue samples, followed by detection using enzyme-linked secondary antibodies that generate a colored precipitate at the site of binding. Common chromogens include DAB, producing a brown signal, and AEC, generating a red signal, typically contrasted against a blue hematoxylin nuclear counterstain.

Standard Workflow

• Fixation of tissue samples (commonly using formalin)
• Paraffin embedding and sectioning (approximately 4 µm thickness)
• Deparaffinization and rehydration
• Antigen retrieval (heat-induced or enzymatic methods)
• Blocking of non-specific binding sites
• Incubation with primary antibody (typically overnight)
• Application of secondary antibody conjugated to an enzyme
• Chromogen development
• Counterstaining and mounting